1. Field of the Invention
The present invention relates to a novel powdered tobermorite-type calcium silicate-based material and to a method for producing the same.
2. Description of the Related Art
Calcium silicate is a compound that has a long history and consists of both natural and synthetic forms. In addition, known crystal forms of calcium silicate include gyrolite, wollastonite and tobermorite. Calcium silicate is used in various applications, including building materials (such as lagging materials, refractory materials or heat insulating materials), as well as pharmaceutical additives, food additives, fillers, thickeners, matting agents and carriers.
Among these various types of calcium silicate, calcium silicate having high oil absorption in particular is used in pharmaceutical additives such as excipients, carriers, binders or disintegrating agents, as carriers of liquid substances in cosmetic and industrial fields, and as carriers of perfumes or oxygen adsorbing agents. Since tobermorite-type calcium silicate in particular has a higher specific surface area than other crystal forms and is superior for use as a carrier, research is proceeding on the development of porous materials of tobermorite-type calcium silicate.
A known example of a method used to produce calcium silicate consists of producing calcium silicate (tobermorite crystals) from a silicic acid raw material and a calcareous raw material by a hydrothermal synthesis reaction (for example, Japanese Patent Application Publication No. H06-329409 or Japanese Patent Application Publication No. H06-40715).
On the other hand, as a method that does not use a hydrothermal reaction, a method for producing porous calcium silicate has been proposed, which includes: a slurry formation step of blending a silicic acid raw material and a lime raw material within a range of the molar ratio of CaO/SiO2 of 0.4 to 1.0 followed by adding water and suspending to form a slurry; a mechanochemical reaction step of simultaneously agitating and crushing the formed slurry using a wet grinder to produce a mechanochemical reaction; and a heat curing step of heat-curing the slurry following the mechanochemical reaction while agitating (Japanese Patent Application Publication No. 2004-43290).